The invention relates to an electrophotographic recording material which consists of polyphenylenevinylenes and low-molecular organic additions.
Polyphenylenevinylenes consist of a conjugated sequence of unsubstitued or substituted phenylene and vinylene structure members which can be arranged in alternation according to formula (1) or not alternating according to formula (2). ##SPC1##
A plurality of alternating polyphenylenevinylenes, known as polyxylylioenes according to formula (1) is already known. They differ from one another by the nature and position of the substituents R.sub.1 to R.sub.6 and by the succession of variously substituted blocks. Furthermore cocondensates are known which correspond to formula (2).
Apart from structure features such as arrangement, relationship of the blocks and nature of the substituents R, the mean molecular weight must also be used for the characterisation of these polymers. Such polyphenylenevinylenes are photoconductive, possess a high dark resistance and have already been proposed, beside other low molecular and polymeric organic photoconductors, for use for electrophotography. Several such polyphenylenevinylenes, for example those with R.sub.1 and/or R.sub.6 equal to phenyl, are soluble and can be processed into coatings.
On account of the low characteristic sensitivity of almost all organic photoconductors, additions of dyestuffs and/or electron acceptors as sensitisors have been proposed for the production of sensitive electrophotographic coatings.
Both types of sensitisor often however possess the disadvantage that their chemical and photochemical stability is not satisfactory. For example some dyestuff additives bleach out, like the merocyanine dyestuffs, or chemical modifications of the coatings occur in storage or use, as in the case of use of Lewis acids or strong electron acceptors (tetracyanoethylene). Moreover a series of additives which have been proposed to increase sensitivity in organic polymeric photoconductors leads to a deterioration of the optical properties, especially of homogeneity (transparency and lightpermeability in the visible range, detrimental to the use).